i'm still thinking about it...
I come fromt the electro-industrial scene ( i am not really in psytrance in deed ). and there's a dark-electro band, Apoptygma Berzerk, which has also made a cover of the Bach Tocata & Fugue. I remember I heard it long ago. it is really likely to have vocals.
the dark-electro scene is heavily inspired by some similar sounds and patterns like trance... but much darker in general. ( more goth :-) )
it could be your track also.